Cathode-ray tube manufacturing apparatus



Sept. 5, 1967 T. J. HAJDUK 3,340,035

CATHODE-RAY TUBE MANUFACTURING APPARATUS Filed Sept. 28, 1964 2Sheets-Sheet l 2. T53 34 FIG.1

O O Q INVENTOR S Thaddeafirl 20 5 u 'Hd Kow Sept. 5, 1967 T. J. HAJDUK3,340,035

CATHODERAY TUBE MANUFACTURING APPARATUS Filed Sept. 28, 1964 2Sheets-Sheet 2 FIG. 3

VENTORS "if I 4 22 A 5 5o 7 THADDEU HAJDUK G| FRED :yALsm BY MMLA/United States Patent 3,340,035 CATHODE-RAY TUBE MANUFACTURING APPARATUSThaddeus J. Hajduk, Chicago, and Fred Kowalski, Park Ridge, [1].,assignors to The Rauland Corporation, Chicago, Ill., a corporation ofIllinois Filed Sept. 28, 1964, Ser. No. 399,478 11 Claims. (Cl. 65-454)The present invention concerns an apparatus for making an electron gunassembly for a three-gun cathoderay tube such as currently used in colortelevision receivers. The invention is directed, more particularly, towhat is referred to as beading and comprises an improved apparatus foraccomplishing this step in the manufacture of a multi-gun tube.

It is convenient to describe the invention in the environment of acathode-ray tube in which the electron gun assembly includes cylindricalelectrodes for controlling, forming and focusing into a beam electronsemitted by a heated cathode. It is common practice to provide each ofthe electrodes with mounting straps spaced on the external periphery ofthe electrode. If the electrode series of a gun is mounted on a suitablemandrel with interposed spacers, the electrodes may conveniently bearranged in a desired array and with chosen interelectrode spacings.Generally, the electrodes are rotatable on the mandrel to the end thattheir mounting straps may be aligned. If the straps are now embedded inelongated pillars of insulating material, referred to as beadingelements, the electrode series will have been formed into an array withpreselected interelectrode spacings.

This subassembly has been formed heretofore by depositing a beadingelement in a holder and heating an exposed surface thereof until it hassoftened. Thereafter, the electrode series supported on its mandrel ispositioned over and in alignment with the beading element and the strapsare then forced into its softened surface. After a suflicient coolingperiod, the bead sets and its affixation to the mounting straps of theelectrodes is complete. Repeating this process puts a 'second bead onthe other series of straps of the assembled electrodes and completes thesubassembly. Although this practice is acceptable, it is time consumingand, accordingly, it has been proposed that both beads be applied at thesame time. While such a procedure may be readily established for asingle gun assembly, it presents formidable problems when attempted fora three-gun color tube assembly. In such an assembly, it is commonpractice to employ mechanical convergence so that the position of theelectron guns relative to one another is most important and misaligningof the electrodes on their respective mandrels during the beadingoperation can easily lead to a reject assembly. And yet, it is highlydesirable both to speed up the beading function and to perform it in away which minimizes the possibility of impairing the electrodealignment. These objectives are satisfied through the apparatus to bedescribed.

Accordingly, it is a principal object of the invention to provide animproved apparatus for performing the beading operation in themanufacture of a multi-gun assembly.

It is another and specific object of the invention to provide anapparatus for making the three-gun assembly of a color cathode-ray tubewhich minimizes the possibility of misaligning the gun elements relativeto each other.

The three guns constituting the gun assembly of a tricolor cathode-raytube individually include cylindrical electrodes each of which has apair of mounting straps angularly spaced approximately 120 on theexternal periphery thereof. The beading apparatus of the invention forassembling the three guns comprises a workholder including threemandrels positioned at the apices of an equilateral triangle forindividually supporting the electrodes and interposed spacing elementsof each of the three guns to establish a preselected electrode arraywith predetermined interelectrode spacings and with the mounting strapsof each of the guns in substantial alignment and in approximate parallelrelation to straps of the remaining two guns. Three bead holdersindividually releasably hold an elongated beading element of insulatingmaterial for movement between a heating position and a beading position.Means are provided for heating one surface of each of the headingelements to a softened condition. There are further means forsimultaneously displacing each of the bead holders from its heatingposition to its beading position to drive the straps of two of the gunsinto each one of the beading elements and for retracting each of thebead holders from its beading position after a predetermined coolingperiod.

The mechanism for displacing the bead holders preferably features alinkage system similar to that of an umbrella in that a sleeve,displaced along a vertical shaft, moves the three bead holderssimultaneously. It is also preferred that the sleeve be crank driven toexecute harmonic motion, moving slowly from the heating position, thenaccelerating to approach the beading position quickly and finallydecelerating to be presented to the beading position with minimumimpact.

The features of the present invention which are believed to be novel areset forth with particularity in the appended claims. The invention,together with further objects and advantages thereof, may best beunderstood by reference to the following description taken in connectionwith the accompanying drawings, in the several figures of which likereference numerals identify like elements, and in which:

FIGURE 1 is an elevational view of the beading apparatus of theinvention to be used in fabricating the gun assembly of a three-guntri-color cathode-ray tube;

FIGURE 2 is a view, partially in section, taken along line 2-2 of FIGURE1;

FIGURE 3 is an enlarged detailed view taken on line 33 of FIGURE 2; and

FIGURE 4 is an enlarged detailed view of the section designated by aline 4-4 of FIGURE 3.

The beading apparatus comprises a removable workholder or fixture 10.The use of a removable fixture is convenient in that it permits thecomponents of the three guns to be assembled at one work station andthen loaded into the beading machine to receive its beading elements.The workholder has a base 11 which supports three mandrels positioned atthe apices of an equilateral triangle. As shown more clearly in FIGURE3, base 11 has a central hub-like section 12 with three longitudinallyextending apertures each of which receives one mandrel 13. The threemandrels, particularly a to the portions thereof which serve to supportthe gun electrodes during the beading ope-ration, are the samestructurally with one portion of nearly the same dimension as the innerdiameter of a cylindrical electrode G One end of electrode G has one ormore orienting straps 16 to be received in slots 15 milled in the uppersurface of hub section 12 of workholder 10. If electrode G is threadedover the mandrel with its tab 16 inserted into slot 15, this electrodeis supported in a predetermined orientation and against rotation. Thenext element threaded over the mandrel is a spacer 17 which is followedby an electrode G One end of this electrode has a reduced diametersection and mandrel 13, likewise, has a reduced diameter section 18which accommodates the smaller end of electrode G The next succeedingelement of the stack is a spacer 19 followed by a' cylindrical electrodeG One end of electrode G is closed but has a central aperture foradmitting an electron beam. The mandrel is stepped down in dimensionsuccessively with a section 20 which corresponds to the opening providedin the reduced section of electrode G to a final section 21 whichmatches in diameter the aperture of electrode G and the beam aperture ofa further electrode G which is spaced from G by a spacer 22.

The enlarged view of FIGURE 4 illustrates the location of the threemandrels at the apices of an equilateral gun triangle. This view alsoillustrates that the cylindrical electrodes are provided with mountingstraps angularly spaced on their external periphery. More particularly,each electrode has a band 25 with a span of approximately 120 afiixed toits outer periphery and the free ends 26 of the band serve as theelectrode mounting straps. Obviously, each mandrel 13 has a lengthsufficient to accommodate the electrode series and also to be receivedwithin its recess in hub section 12 as a support.

In the three-gun assembly, it is conventional practice to have the gunsmechanically converged rather than being supported with their axesparallel to one another. This is done to ease the convergence problem ofthe color tube into which the gun assembly is to be incorporated. Sincethe guns are mechanically converged, it is helpful to arrange that atleast two, if not all three, of mandrels 13 recede within hub 12 offixture 10. Accordingly, the length of the mandrel is sufiicient toproject through hub 12 and its lower extremity has a fitting 28 with afinger piece 28a that may be grasped by an operator to rotate thespindle about its own axis. There is also a locking flange 28b which mayrest upon a stop 29 suspended from base 11. With this structure, themandrel may be locked in the position shown in FIGURE 3 and retained inthat position while the electrodes G G and spacer elements 17, 19, 22are threaded thereover. It is also retained in this position throughoutthe heading operation. When that operation has been completed and thesubassembly is to be removed, finger piece 28a may be rotated to releasethe mandrel permitting it to descend within hub 12 and facilitatingremoval of the subassembly. The fixture is sufiiciently flexible if twoof mandrels 13 are adjustable in the described fashion and a pair ofsuch mandrels is illustrated in FIGURE 3. The third may or may not bepermanently fixed in the beading position.

It will be observed in FIGURE 3 that a support post 30 extendsvertically from hub 12 in parallel relation to an assigned mandrel 13and the free end of each spacer element 17, 19, 22 threads thereover. Byvariously shaping the cross section of this support post at differentlevels with a matching configuration at the terminal portions of thespacers, keying may be introduced to assist the operator in arrangingthe spacers only in their preferred order in the electrode stack. Ofcourse, a similar support post is associated with each of the threemandrels.

A pressure pad 31 rests within electrode G It may be put under pressureto clamp the electrodes during a bead ing operation. To that end, thepad is carried at the free end of a clamp lever 32 which is pivoted at33 to a stand 34 secured to base 11. A handle 36 is also pivoted tostand 34 at point 36a and is coupled to lever 32 by means of a link 37pivoted at 37a to handle 36 and at 37b to lever 32. Link 37 also carriesa pressure block 370 for engaging lever 32 acting as a stop. Acompression spring 35 is interposed between pad 31 and lever 32. Ifhandle 36 is rotated clockwise about its pivot 36a, lever 32 rotates inthe same direction about its pivot 33 and pad 31 is moved clear of theaxis of mandrel 13, freeing the mandrel for loading or unloading. Whenthe mandrel has been loaded with electrodes 6 -6 and the interelectrodespacers, preparatory to a beading operation, handle 36 is rotated in acounterclockwise direction to the position shown in FIGURE 3. This moveslever 32 in the same direction and inserts pad 31 into electrode G Stopblock 370 rests on lever 32 and all pivots 36a, 37a and 37b are insubstantial alignment locking lever 32 against upward movement untilsuch time as handle 36 shall have been rotated in a clockwise direction.Consequently, the electrode stack supported by mandrel 13 is clampedunder pressure during the beading operation.

As shown in the enlarged view of FIGURE 4, base 11 has three armsextending from hub 12 and spaced approximately 120 apart. A rod 40extends downwardly from each of the radial arms of base 11 andcollectively the three rods serve as legs upon which fixture 10 is ableto rest while the electrode elements and spacers are threaded on theseveral mandrels, this of course being accomplished at a loading stationand not with the fixture installed in the beading machine.

Again with particular reference to FIGURE 4, it is clear that inthreading electrode elements over mandrels 13, bands 25 of allelectrodes are positioned inwardly toward the center of the gunassembly. Additionally, the straps 26 are formed or shaped so that whenthe .electrodes are properly oriented about their individual mandrels,the electrode straps of each gun are in approximate parallel relation toelectrode straps of the remaining two guns. This is illustrated inFIGURE 4 and the precise orientation is achieved by means of a splinegauge 43. The spline gauge has a web at the top and'three dependingfingers 43a, one shown in FIGURE 3, which may be threaded down betweenthe pairs of the parallel arranged straps 26 to establish the desiredorientation of the various electrode series. Gauge 43 is retained inposition throughout the beading process.

Workholder 10 is removably installed in a framework secured to thehorizontal or table portion 45 of the beading machine. The frame hasthree elements 46 which are essentially Z-shaped and, as shown in FIGURE3, a thin plate 47 extends from the under face of the top'free end ofeach such element to serve as a shelf .upon which one arm of fixturebase 11 may rest. It is essential that workholder 10 not only besupported within the beading apparatus but it must also be properlyoriented in order that the beading elements may be presented in a properrelation to electrode straps 26 to which they are to be attached. Forthat reason, one end 46a of each of the support elements 46 serves as astop against which the arm of base 11 which it supports is to come torest in determining the orientation of fixture 10 within the beadingmachine. As indicated in FIGURE 4, stop portion 46a may have a flangesection under which an arm of base 11 is to slide so that once thefixture has been properly horned within the beading machine it must berotated in a counterclockwise direction to be removed. This facilitatesan interlock protection that will be described. One of the supportelements 46 carries a clamp (FIGURE 2) which may be manually closedagainst one of the arms of base 11 of fixture 10 to retain the fiixturelocked securely in position in the beading machine. The detail of FIGURE4 shows the clamp 80a engaging an arm of base 11 in this lockingfunction.

The interlock to which reference has been made is designated 52 inFIGURE 2. It is supported on horizontal shelf 45 of the heading machineand is a microswitch 52 with a switch operator 52a projecting radiallyinwardly toward the center of fixture 10 but beneath the'level of itsbase 11. In this position, it is in the path of a leg 40 of the fixtureso that counterclockwise rotation of'the fixture required to release itfrom the beading machine actuates microswitch 52.

The beads to be attached to the electrode straps are made of glass orinsulating ceramic material and are releasably held by three beadholders for movement between a heating position and a heading position.One of the three bead holders 51 is shown in detail in FIGURES 3 and 4.It comprises a block 51a with a slot 51b dimensioned to receive one ofthe beading elements 50.It is preferred that the slot beelectro-polished to prevent the slot 51b by spring-pressed fingers orclamps 51c, 51d

a) pivoted to the body of holder 51 and urged in clamping positions bysprings 51e. Each finger may engage an end of bead 50 releasably toretain the bead within slot 51b of holder 51.

It would be unproductive to perform a beading cycle unless each of thethree holders 51 contained a beading element. Consequently, each holder51 accommodates a microswitch 51 that may be actuated by a fingerportion 51g of clamp 51c. With a beading element in position,microswitch 51 will have been actuated to permit the beading operationto be pe formed, whereas in the absence of a beading element, finger 51cassumes an extreme clockwise position and opens microswitch 51 toprevent a beading cycle. As illustrated in FIGURE 3, holder 51 is in aheading position presenting bead 50 to the aligned electrode mountingstraps 26.

The heating position of the bead holder is that shown in FIGURES 1 and 2where the means for heating one surface of each beading element 5! to asoftened condition are heaters 53. There is associated with each heatera pair of starting electrodes 53a. These electrodes are energized whenit is desired to ignite the heater in order to soften beads 50 in theheading cycle. The conduits 53b indicate gas lines which feed theheaters.

Movement of each holder 51 between its heating and beading positions isalong a median line of the gun triangle. To that end, each bead holder51 is pivoted at 51h to a sleeve 45a affixed to the frame of the machineand is moved by means of links 54 which connect at one end to the beadholder so that movement of link 54 may displace the bead holder aboutits pivot 51h. Preferably, an eccentric is employed as the pivot pincoupling link 54 to holder 51 in order to facilitate adjustment of thebeading depth. Since the three-gun beading machine has three suchholders there are three links 54 and a common actuator connects to theirfree ends in order that they may be displaced simultaneously.Preferably, the common actuator is a sleeve 54a (FIGURE 1) slidable upona vertical post 54b which is disposed coaxially of the triangleincluding the gun mandrels. That is to say, the axis of post 54b extendsthrough the center of the gun triangle. Sleeve 54a has three flanges 54cand a pin pivotally connects each flange to the lower end of a link 54.Post 54b is supported by sleeve 45a and a shelf 45b constituting a partof the stationary frame of the beading machine.

In order to accomplish a beading cycle, it is necessary to slide sleeve54a first vertically upwardly and then downwardly of post 54b. This isaccomplished by means of a driving motor 75 which is coupled through aspeed re ducing arrangement 75a to a solenoid controlled halfrevolutionclutch 75b. The clutch affords a coupling to a crank 750 which connectsto one end of a pivoted lever 75d. The opposite end of that leverterminates in a fork 752 which engages pins 75 projecting from oppositesides of sleeve 54a. This completes a coupling frommotor 75, through thespeed reduction arrangement 75a, clutch 75b, crank 75c and lever 75d tosleeve 54a.

A programming arrangement 62, not shown in detail because it is ofconventional construction, controls the circuitry by which the machineis placed into operation to perform the heading cycle when a startingswitch (not shown) has been actuated. The circuits programmed therebyinclude the control for the solenoid which permits clutch 75b to respondand institute a half revolution drive of the clutch at particularintervals in the beading cycle. It further includes an excitationcircuit for ignition electrodes 53a to fire heaters 53 only duringcertain program intervals. And, its control circuits further includemicroswitches 51f and 52 arranged so that beading cannot be accomplishedunless each workholder 51 contains a bead ing element 50 and alsopreventing what is known as double beading.

In describing the operation of the beading apparatus, it will be assumedthat fixture is initially removed from the beading machine and is to beloaded with the cylindrical electrode elements from which a three-gunassembly is to be fabricated. With fixture 10 in its loading station,finger portions 28a are manipulated to raise mandrels 13 and lock themin the position shown in FIGURE 3. It is assumed now that all threemandrels are elevated and in position to receive the electrode elements.The loading is the same for each mandrel.

First grid G is placed on the mandrel and oriented by inserting tab 16into slot 115. This is followed by stacking on the mandrel spacer 17,grid G spacer 19, grid G spacer 22 and finally grid G Each electrode ispositioned with its band 25 facing toward the center of the guntriangle. When all of the mandrels have been threaded or loaded withthese elements, spline gauge 43 is inserted between the aligned andapproximately parallel pairs of straps 26 as indicated in FIGURE 4. Thespline gauge orients electrodes G G from or with reference to electrodeG which is held against rotation by its tab 16 which is nested withinslot 15 of base 11. This establishes the electrodes of each gun in apreselected array on its mandrel with predetermined interelectrodespacings and with the mounting straps of each gun in alignment and inparallel relation to straps of the other two guns. Handle 36 is nowrotated in a counterclockwise direction to bring clamp pad 31 intoelectrode G of one gun and to apply a clamping pressure to all theelectrodes thereof. This clamping is similarly performed for each of thegun assemblies and fixture 10 is now loaded and ready to be installed inposition in the beading machine.

It will be assumed that sleeve 54a is in its lowermost position(FIGURE 1) presenting all the bead holders 51 to the heating position.The frame 46 for receiving beading fixture -10 is now readily accessibleand the fixture is inserted, resting upon shelves 47 and turned in aclockwise direction to home the arms of base 11 against stops 46a. Lockis now actuated releasably locking fixture 10 in the beading machine andwith the appropriate orientation.

While holders 51 are in the heating position and heaters 53 are olf, anoperator manually loads the heading elements 50 in each such holder.Loading of the bead in each holder actuates microswitches 51 which isnecessary to condition timer 62 to control a beading cycle. When holders51 have all been loaded and fixture 10 has been properly secured inposition, the starting switch is actuated. It is distinctly preferredthat the machine be provided with a pair of starting switches requiringthe operator to use both hands to initiate the cycle. These switches areplaced at the peripheral portion of the machine so that the operatormust be away from the heaters before the starting switches may beactuated.

When the starting switch has been closed, timer 62 is energized andapplies a potential for a very short interval to starting electrodes 53aof each heater. The timer also opens a valve (not shown) which suppliesgas to the heaters which are now fired. The fires are trained on theexposed face of each bead 50 and after a suitable heating interval,usually three seconds, that surface of the beads becomes sufficientlysoft that a mounting strap may readily be inserted into it. At thispoint, timer 62 shuts off the gas supply to the heaters.

After the heating interval has passed, timer 62 energizes the solenoidcontrolling clutch 75 to permit one half revolution. In thishalf-revolution of the clutch, crank 75c and lever 75d slide sleeve5411: up post 54b. This simultaneously displaces each of bead holders 51from its heating position of FIGURE 1 along a median line of one side ofthe gun triangle to its beading position of FIGURE 3. The softenedsurfaces of the beads are driven against electrode straps 26, each beadbeing driven against two aligned and parallel series of straps 26. Sincethe arrangement is symmetrical and the beads are applied simultaneouslywith the same force against the three alignments of mounting straps, theforces are symmetrical and balance out so that there is no net forcetending to disturb the .alignment of the electrodes on their mandrels.Moreover, the halfrevolution clutch 75b causes the motion or action ofbead holders 51- to be harmonic, that is to say, the action startsslowly and smoothly, accelerates rapidly and then terminates in asmooth, constant deceleration. This permits fast action of the beadholders to prevent chilling of the beads and yet presentation of thebeads to straps 26 without a shock force that would tend to distort anddisturb the alignment accuracy of the guns in the gun triangle. Holders51'are retained in their beading position for a cooling period duringwhich the beads set and become integrated with straps 26. An interval of15 seconds is usually sufficient. After the cooling interval, programtimer 62 again energizes clutch 75d and sleeve 54a is returned to theposition of FIGURE 1, displacing holders 51 from the beading to theheating position. Inasmuch as each holder releasably supports a bead 50,the return of the holders to the heating positions strips the beads fromthe holders, leaving the beads in an integrated assembly with theelectrode series of the three-gun assembly. At this juncture, timer 62will have completed its cycle, a heading operation shall have beenfinished and the machine shut oil.

The operator may now remove fixture 10 from the machine. This isaccomplished by rotating the fixture in a counterclockwise directionwhich actuates microswitch 52 and prepares timer 62 for the nextsucceeding beading operation. With the fixture removed from the headingmachine, spline gauge 43 is removed from the gun assembly. This isaccomplished by inserting a knock out pin in the center and at thebottom of the multi-gun assembly. Finger pieces 28 are again manipulatedto withdraw mandrels 13 from the gun assemblies. The assembly may now beremoved from the workholder and its spacer elements may, likewise, bewithdrawn freeing the completed three-gun assembly. This is to say,completed insofar as the electrodes have been secured to insulatingposts 50 to maintain the electrodes in a preselected array with apredetermined interelectrode spacing and with a predetermined electrodealignment.

Switch 72 must be actuated before a second beading cycle is initiatedand actuation of this switch is accomplished by removing workholder 10from the machine. Accordingly, double beading or a multiplicity ofbeading cycles cannot be performed on a single assembly of electrodeelements.

While a particular embodiment of the present invention has been shownand described, it is apparent that changes and modifications may be madetherein without departing from the invention in its broader aspects. Theaim of the appended claims, therefore, is to cover all such changes andmodifications as fall within the true spirit and scope of the invention.

We claim:

1. Apparatus for making a three-gun assembly for a cathode-ray tubeindividually including cylindrical electrodes each of which has a pairof mounting straps angularly spaced approximately 120 degrees on theexternal periphery thereof, said apparatus comprising:

a workholder including three mandrels positioned at the apices of anequilateral triangle for individually supporting the electrodes andinterposed spacing elements of each of said guns to establish therfor apreselected electrode array with predetermined interelectrode spacingsand with said mounting straps of each of said guns in substantialalignment and in approximate'parallel relation to straps of theremaining two guns;

three bead holders for individually releasably holding an elongatedbeading element of insulating material for movement between a heatingposition and a beading position;

means for heating one surface of each of said beading elements to asoftened condition;

and means for simultaneously displacing each of said head holders fromits heating position to its beading position to drive said straps of twoof said guns into each of said beading elements and for retracting eachof said bead holders from its beading position after a predeterminedcooling period. 2. Apparatus for making a three-gun assembly for acathode-ray tube individually including cylindrical electrodes each ofwhich has a pair of mounting straps angularly spaced approximately 120degrees on the external periphery thereof, said apparatus comprising:

a workholder including three mandrels positioned at the apices of anequilateral triangle for individually supporting the electrodes andinterposed spacing elements of each of said guns to establish therefor apreselected electrode array with predetermined interelectrode spacingsand with said mounting straps of each of said guns in substantialalignment and in approximate parallel relation to straps of theremaining two guns;

three bead holders for individually releasably holding an elongatedbeading element of insulating material for movement between a heatingposition and a beading position;

means for heating one surface of each of said beading elements to asoftened condition;

and means for simultaneously displacing each of said head holders fromits heating position to its beading position to drive said straps of twoof said guns into each of said beading elements and for retracting eachof said bead holders from its beading position after a predeterminedcooling period, said displacing means moving said bead holders withequal force along median lines of said triangle to exert balancedpressures against said guns.

3. Apparatus for making a three-gun assembly for a cathode-ray tubeindividually including cylindrical electrodes each of which has a pairof mounting straps angularly spaced approximately 120 degrees on theexternal periphery thereof, said apparatus comprising:

.a workholder including three mandrels positioned at the apices of anequilateral triangle for individually supporting the electrodes andinterposed spacing elements of each of said guns to establish therefor apreselected electrode array with predetermined interelectrode spacingsand with said mounting straps of each of said guns in substantialalignment and in approximate parallel relation to straps of the remaining two guns;

three bead holders for individually releasably holding an elongatedbeading element of insulating material and individually mounted forpivotal movement along a median line of said triangle between a heatingposition and a beading position;

means for heating one surface of each of said beading elements to asoftenedcondition;

and means for simultaneously displacing each of said bead holders fromits heating position to its beading position to drive said straps of twoof said guns into each of said beading elements and for retracting eachof said bead holders from its beading position after a predeterminedcooling period said displacing means comprising a mechanism forefiecting harmonic motion of said bead holders between its aforesaidpositions.

4. Apparatus for making a three-gun assembly for a cathode-ray tubeindividually including cylindrical electrodes each of which has a pairof mounting straps angularly spaced approximately 120 degrees on theexternal periphery thereof, said apparatus comprising:

a workholder including three mandrels positioned at the apices of anequilateral triangle for individually supporting the electrodes andinterposed spacing elements of each of said guns to establish therefor apreselected electrode array with predetermined interelectrodespacings'and with said mounting straps of each of said guns insubstantial alignment and in approximate parallel relation to straps ofthe remaining two guns;

three bead holders for individually releasably holding an elongatedbeading element of insulating material and individually mounted forpivotal movement along a median line of said triangle between a heatingposition and a beading position;

means for heating one surface of each of said beading elements to asoftened condition;

a link for each of said bead holders connected at one end to itsassociated bead holder for effecting pivotal displacement thereofbetween a heating position and a heading position;

a common actuator connected to the other end of each -of said links anddisplaceable to move said three bead holders simultaneously;

and a timer for displacing said actuator to move said bead holders tosaid beading position after said beading elements have been softened andto return said bead holders to said heating position after a givencooling period.

5. Apparatus for making a three-gun assembly for a cathode-ray tubeindividually including cylindrical electrodes each of which has a pairof mounting straps angularly spaced approximately 120 degrees on theexternal periphery thereof, said apparatus comprising:

a workholder including three mandrels positioned at the apices of anequilateral triangle for individually supporting the electrodes andinterposed spacing elements of each of said guns to establish therefor apreselected electrode array with predetermined interelectrode spacingsand with said mounting straps of each of said guns in substantialalignment and in approximate parallel relation to straps of theremaining two guns;

three bead holders for individually releasably holding an elongatedbeading element of insulating material and individually mounted formovement along a median line of said triangle between a heating positionand a heading position;

means for heating one surface of each of said beading elements to asoftened condition;

a link for each of said bead holders connected at one end to itsassociated bead holder for effecting displacement thereof between aheating position and a heading position;

a vertical support extending coaxially of said triangle;

a sleeve slidable on said vertical support and connected to the otherend of each of said links to move said three bead holderssimultaneously;

and means for displacing said sleeve along said vertical support.

6. Apparatus for making a three-gun assembly for a cathode-ray tubeindividually including cylindrical electrodes each of which has a pairof mounting straps angularly spaced approximately 120 degrees on theexternal periphery thereof, said apparatus comprising:

a workholder including three mandrels positioned at the apices of anequilateral triangle for individually supporting the electrodes andinterposed spacing elements of each of said guns to establish therefor apreselected electrode array with predetermined interelectrode spacingsand with said mounting straps of each of said guns in substantialalignment and in approximate parallel relation to straps of theremaining two guns;

three bead holders for individually releasably holding an elongatedbeading element of insulating material and individually mounted formovement along a median line of said triangle between a heating positionand a beading position;

means for heating one surface of each of said beading elements to asoftened condition;

a link for each of said head holders connected at one end to itsassociated bead holders for eifecting displacement thereof between aheating position and a beading position; a vertical support extendingcoaxially of said triangle; a sleeve slidable on said vertical supportand connected to the other end of each of said links to move said threebead holders simultaneously; and means including a drive motor, ahalf-revolution clutch, and a crank connected to said sleeve fordisplacing said sleeve along said vertical support. 7. Apparatus formaking a three-gun assembly for a cathode-ray tube individuallyincluding cylindrical electrodes each of which has a pair of mountingstraps angularly spaced approximately degrees on the external peripherythereof, said apparatus comprising:

a workholder including three mandrels positioned at the apices of anequilateral triangle for individually supporting the electrodes andinterposed spacing elements of each of said guns to establish therefor apreselected electrode array with predetermined interelectrode spacingsand with said mounting straps of each of said guns in substantialalignment and in approximate parallel relation to straps of theremaining two guns;

clamps included in said workholder and individually associated with oneof said mandrels for maintaining the electrode array of each of saidmandrels under a predetermined clamping pressure during the beadingoperation;

three bead holders for individually releasably holding an elongatedbeading element of insulating material for movement between a heatingposition and a beading position;

means for heating one surface of each of said beading elements to asoftened condition;

and means for simultaneously displacing each of said bead holders fromits heating position to its beading position to drive said straps of twoof said guns into each of said beading elements and for retracting eachof said bead holders from its beading position after a predeterminedcooling period.

8. Apparatus for making a three-gun assembly for a cathode-ray tubeindividually including cylindrical electrodes each of which has a pairof mounting straps angularly spaced approximately 120 degrees on theexternal periphery thereof, said apparatus comprising:

a workholder including three mandrels positioned at the apices of anequilateral triangle for individually supporting the electrodes andinterposed spacing elements of each of said guns to establish therefor apreselected electrode array with predetermined interelectrode spacingsand with said mounting straps -of each of said guns in substantialalignment and in approximate parallel relation to straps of theremaining two guns;

three bead holders for individually releasably holding an elongatedbeading element of insulating material for movement between a heatingposition and a beading position;

each of said head holders including a pair of spring pressed clamps forengaging the opposite ends of one of said beading elements;

means for heating one surface of each of said beading elements to asoftened condition;

and means for simultaneously displacing each of said bead holders fromits heating position to its beading position to drive said straps of twoof said guns into each of said beading elements and for retracting eachof said head holders from its beading position after a predeterminedcooling period.

9. Apparatus for making a three-gun assembly for a cathode-ray tubeindividually including cylindrical electrodes each of which has a pairof mounting straps angularly spaced approximately 120 degrees on theexternal periphery thereof, said apparatus comprising:

a workholder including three mandrels positioned at the apices of anequilateral triangle for individually supporting the electrodes andinterposed spacing elements of each of said guns to establish therefor apreselected electrode array with predetermined interelectrode spacingsand with said mounting straps of each of said guns insubstantial'alignrnent and in approximate parallel relation to straps ofthe remaining two guns;

three bead holders for individually releasably holding an elongatedbeading element of insulating material for movement between a heatingposition and a beading position;

means for heating one surface of each of said beading elements to asoftened condition;

means for simultaneously displacing each of said head holders from itsheating position to its beading position to drive said straps of two ofsaid guns into each of said beading elements and for retracting each ofsaid bead holders from its beading position after a predeterminedcooling period;

and a program timer for firing said heating means for a given intervalat the start of a heading cycle, and for controlling said displacingmeans to move said bead holders to said beading position after saidgiven interval and to displace said bead holders from said beadingposition to said heating position after a given cooling period.

10. Apparatus for making a three-gun assembly for a cathode-ray tubeindividually including cylindrical electrodes each of which has a pairof mounting straps angularly spaced approximately 120 degrees on theexternal periphery thereof, said apparatus comprising:

a removable workholder including three mandrels positioned at the apicesof an equilateral triangle for individually supporting the electrodesand interposed spacing elements of each of said guns to establishtherefor a preselected electrode array with predetermined interelectrodespacings and with said mounting straps of each of said guns insubstantial alignment and in approximate parallel relation to straps ofthe remaining two guns;

three bead holders for individually releasably holding an elongatedbeading element of insulating material for movement between a heatingposition and a beading position;

means for heating one surface of each of said beading elements to asoftened condition;

means for simultaneously displacing each of said head holders from itsheating position to its beading position to drive said straps of two ofsaid guns into each of said beading elements and for retracting each ofsaid bead holders from its beading position after a predeterminedcooling period;

a program timer for firing said heating means for a given interval atthe start of a beading cycle, and for controlling said displacing meansto move said bead holders to said beading position after said giveninterval and to displace said bead holders from said beading position tosaid heating position after a given cooling period;

and an interlock actuated by removal of said workholder for conditioningsaid program timer for controlling a heading cycle.

11. Apparatus for making a three-gun assembly for a cathode-ray tubeindividually including cylindrical electrodes each of which has a pairof mounting straps angularly spaced approximately 120 degrees on theexternal periphery thereof, said apparatus comprising:

a workholder including three mandrels positioned at the apices of anequilateral triangle for individually supporting the electrodes andinterposed spacing elements of each of said guns to establish therefor apreselected electrode array with predetermined interelectrode spacingsand with said mounting straps of each of said guns in substantialalignment and in approximate parallel relation to straps of theremaining two guns;

three bead holders for individually releasably holding an elongatedbeading element of insulating material for movement between a heatingposition and a beading position;

means for heating one surface of each of said beading elements to asoftened condition;

means for simultaneously displacing each of said bead holders from itsheating position to its beading position to drive said straps of two ofsaid guns into each of said beading elements and for retracting each ofsaid bead holders from its beading position after a predeterminedcooling period;

and interlocks actuated in response to the positioning of said beadingelements in said head holders for preparing said apparatus to initiate aheading cycle.

References Cited UNITED STATES PATENTS 2,600,076 6/1952 Schelling 65l55XR 2,707,848 5/1955 'Pityo 65-155 XR 2,950,568 8/1960 Kissinger et a1.65l54 DONALL H. SYLVESTER, Primary Examiner.

F. W. MIGA, Assistant Examiner.

1. APPARATUS FOR MAKING A THREE-GUN ASSEMBLY FOR A CATHODE-RAY TUBEINDIVIDUALLY INCLUDING CYLINDRICAL ELECTRODES EACH OF WHICH HAS A PAIROF MOUNTING STRAPS ANGULARLY SPACED APPROXIMATELY 120 DEGREES ON THEEXTERNAL PERIPHERY THEREOF, SAID APPARATUS COMPRISING: A WORKHOLDERINCLUDING THREE MANDRELS POSITIONED AT THE APICES OF AN EQUILATERALTRIANGLE FOR INDIVIDUALLY SUPPORTING THE ELECTRODES AND INTERPOSEDSPACING ELEMENTS OF EACH OF SAID GUNS TO ESTABLISH THERFOR A PRESELECTEDELECTRODE ARRAY WITH PREDETERMINED INTERELECTRODE SPACINGS AND WITH SAIDMOUNTING STRAPS OF EACH OF SAID GUNS IN SUBSTANTIAL ALIGMENT AND INAPPROXIMATE PARALLEL RELATION TO STRAPS OF THE REMAINING TWO GUNS; THREEBEAD HOLDERS FOR INDIVIDUALLY RELEASABLY HOLDING AN ELONGATED BEADINGELEMENT OF INSULATING MATERIAL FOR MOVEMENT BETWEEN A HEATING POSITIONAND A BEADING POSITION; MEANS FOR HEATING ONE SURFACE OF EACH OF SAIDBEADING ELEMENTS TO A SOFTENED CONDITION; AND MEANS FOR SIMULTANEOUSLYDISPLACING EACH OF SAID BEAD HOLDERS FROM ITS HEATING POSITION TO ITSBEADING POSITION TO DRIVE SAID STRAPS OF TWO OF SAID GUNS INTO EACH OFSAID BEADING ELEMENTS AND FOR RETRACTING EACH OF SAID BEAD HOLDERS FROMITS BEADING POSITION AFTER A PREDETERMINED COOLING PERIOD.